1. Field of the Invention
The present invention relates to a separating device for a fluid system having phases of different specific gravities, and more particularly to such a device which includes a plurality of separators in which such a fluid system is swirled about an axis for centrifugal separation of two or more phases and in which the separators are disposed axially of each other for flow of the system through the separators in succession.
2. Description of the Prior Art
The prior art is replete with a variety of separators for separation of a fluid system having phases of differing specific gravities into such phases by centrifugal or vortexing flow of the system within the separator. Such separators have two basic and conflicting objectives. First, the separation of the phases should be as effective as possible. That is, when the separation is complete each of the separated phases should contain as little as possible of the balance of the original fluid system. Second, the pressure drop through such a separator should be as low as possible to minimize energy loss. This second objective is particularly desirable where large quantities of a fluid system require separation, as in the commercial purification of well water. Either one of these objectives can be attained at the sacrifice of the other, but it is of course desirable to provide an arrangement of separators achieving both of the objectives simultaneously. The conflict in these objectives is exemplified where separation of such a fluid system is achieved more effectively by simply causing the fluid to flow through a series of such separators. Such an arrangement provides more effective separation since portions of a phase incompletely separated by a preceding separator can be removed in a succeeding separator. However, the total pressure drop of such an arrangement is usually multiplied by the number of separators in series. The initial expense of such an arrangement is also increased by the number of separation steps involved.
Arrangement of such separators for flow therethrough in series usually results in increased pressure drop, but does not necessarily result in more effective separation since the relative proportions of and remaining constituents of the phases are altered with each separation. For example, where the phases are water and sand, the preceding separator can remove the coarse particles of sand so that the use therewith of a succeeding, identical separator also adapted to removal of such larger particles results in removal of little, if any, additional sand.
Centrifugal separators are commonly disposed in wells below the level of fluid therein at a location at which the fluid is extracted therefrom to remove undesirable phases from the fluid so such phases will not harm other devices through which the water flows upstream of such a location. A typical such usage is the employment of such a separator on the inlet to a submersible pump inserted into a water well to remove sand which rapidly wears such pumps. It is of course desirable to provide highly effective separation in such an application without loss of suction to the pump. Normally the space available in such a well is extremely limited. Thus, a series arrangement of separators used in such an application must be configured so as to be inserted in the confines of a well while providing a flow passage through successive separators which results in minimal pressure drop and does not prevent use of separators adapted to removal of phases of varying characteristics.